Liquid-siren sonic agitator



Nov. 9, 1.954 A. A. FOWLE 2,693,943

LIQUID-SIREN SONIC AGITATOR Filed May 5, 1951 2 Sheets-Sheet l Fig. l

OUTLET g 42 INLET 1 HIGH 54 PRESSURE 38 SUPPLY @Y T 34 32 I0 P /50 /48I8 46 LOW PRESSURE SUPPLY HVVENIUR.

B M M, j mvmm ATTORNEYS United States Patent 6 M The" present inventionrelates:- to apparatus for treat=- ingzbulkiliquidsr with: sound waves:and comprises, in: one aspect, a liquid siren.

Ithas long been'recognizedf that sound-waves of proper frequencies maybe utilized to accomplish many valu+- ableresultsawhen appliedtoliquids. For exarnpleg. sound wavesmay be employed to kill bacteria; .toaccelerate the chemical: processes involved in the ageing: ofalcoholbeverages; to form emulsions; and otherwise improvethe'characteristics'of mans liquids; Attempts havebeen madeto-utilizepiezo-electric crystals and magnetostriction: rodsas the-sourceof'soundwaves in liquids, buttheineffi'ciency of suchoperations onza' largescale has pre-- eluded economic commercial use:thereof;

The-primary object of theinvention is to provide simple" and efficientapparatus' for generating-high intensity sound waves in bulk liquids andthereby to'render commercially feasiblethe sonic treatment thereof.

An important feature of the invention resides in a rotor-statorcombination wherein a liquid is introduced" into the rotor and passedthrough thestator in bursts which. generate pressure waves at sonicorultrasonicfr'equencies, the arrangement of' the rotor with respect toasurrounding housing being such that liquid discharged from the rotordrops at once into a drainage chamber beneath the rotor; wherebythe=rotor spins in air and'is not subject to significant frictional.drag of 'th'e' liquid.

Still another important: feature of the invention resides in a duplexconduit or which one-half serves asa passage for the supply of liquid tothe rotor as well as for the passage of' back-generated'pressure waves;while the other part of the conduit serves for the passage of the liquidto be treated as well as'a continuation of the passage for the pressurewaves, the twoportions of the conduit being separated by a plug "havinganacoustic irn pedance comparable to that of the'liquid' supplied: to'the rotor.

Another feature of the' invention resides in a rotor havingslots soformed that the passage of pressurized fluid therethrough' serves to'spin the rotor..

A very important feature of the invention resides in the=combinationof ahollow'rotor: and a surrounding stator so designed as. to utilize the:pressure. waves generated within. the body of the rotoritself, these.waves traveling backthroughthe rotor and into-a treating chame her. Thiscontrasts with. conventional;operationiin-which 6O thepressurewavesemanating? from the. stator are: applied to do the'desiredwork.While-using. the back-generated waves, itbecomes possible. to spin therotor inv air. in stead ofliquid in. order to reduce significantfrictional drag. Furthermore the flow passages inthe. rotor. maybe.designed so that turbulence within the rotor is avoided; thus increasingthe effective amplitude of the backgenerated waves; Moreoverbysupplying" liquid to the rotor under pressure, cavitation. aflfectingthe; back-generated waves is entirely eliminated, with the result thatpressure wanes of relatively large intensity may begenerated and appliedto do=useful work.

These and other objects and features of the invention will be morereadily understood and appreciated from the following? detaileddescription ofa preferred embodiment thereof. selected for purposes ofillustration and shown in the accompanying drawings in which:

Fig. 1 is a: diagrammatic view of.- a' complete liquid siren and sonictreating system,

Fig. 2. is aview in cross sectionthrough the elements 0 of. therotor-stator combination,

may therefore be 2,693,943 Patented Nov. 9, 1954 Fig: 3:: is a: plan;view of: the: rotor-stator combination; witlr portions.shownzimsectiom.v

Fig;vv 4' is; awiew irr crossssection". onarr-enlarged scale through :a:rotor slot; and" Fig.5

stator ports;

The general organization ofxa'sonic. treating system incorporating animproveddiquidfsiren" isrshown in Fig.1 1 wherein it'wilI. bewevident'that-there is pro.vided a large casing eor housing: 102 of; generallycylindrical shape havmga massive central-boss: 12-.andialso having inits in.- terior anzintegral upstandingtannular flange. 14' provided atits-upper? endi witha series-of: slots: 16;. this serves' as astator;

A' shaft; 18=extendsz through thevboss 12 and. is coupled atitsxlower'xend tosarvariablespeed drive: motor'20'resting'iupon asuitable: base 22'.

Registering: with-.and' secured to the housing 10." is an upper; casing24* having a massive central boss: 26. A hol'low 'rotor-28 is. securedto the upper endof'theshaft 18 within the'wchamben formed by'thehousings 10 and 24. and'ha'sa. 'ollow chamber S'Oand a series: ofperipheral slots' ot portssadapted to register with the slots 16 in thestator ringz14 and to open and close them. as the rotor turns. The rotoris also provided on i'tsupper surface with a centrally'locatedfaperture: 34 surrounding which is a. sealf36 by'means of whichthepassage 34 is'coupled in? watertight relation: to; the. flanged endof a. vertical pipe 38 passing throughthe: boss 26.

A- conduit" 40: connected toarpressure gauge 42. leads to: the. pipe:38? from. a, highpressure: tank. served by" a variable drive pumpdriven: by a motor? 44- and arranged to'supplyliquid. to the: highpressuretank from a sumpor low-pressuretanki connected to the bottom ofthe housing; 10by'a drain-conduit 46 and'connected to the pump by a.conduit: 48; A. by-pass: conduit 50. connects the low pressure or sumptank torthe highpressure tank and is: provided with a. pressure".operated relief valve 52: which maybemanually set to bleed the highpressuretank into the; low pressure tank; at a predetermined pressure;and thereby automatically control the rate of flow of liquid fromthe:high pressure-tank into the pipe 38- and the: rotor28; There is providedin the pipe 38 abovewtheconduit 40 a plug 54- of'solid'material' havinga compressibilitysimilarto thatof'the-liquidin the supply circuitvand-thereby exhibiting anacoustic impedance similarto-that of" the:liquid, which may be oil of the sort commonly used' in' hydraulicsystems. The plug 54 composed of a rubber-like substance bondedrto the.-pipe-walls;

Above the plug 5'4 there is providedrin the-pipe 38 an inlet, and theupper end of the pipe 38 leads to a large surge tank provided? with apressure gauge 56- and also having. an outlet or discharge pipe so thatliquid to be treated. may'ber circulated. through the pipe- 38 and intothe surge tank incontinuous fashion. The pressure gauge 56 permitsobservation astothe pressure in the treating system. v

The. rotor. maybe turned by themotor 20 as liquidis suppliedto it. Theflowof liquid through the rotor is intermittently interrupted as therotor slots 32. pass iii and: out of registry with the stator slots 16.This periodic interruption of the flow of liquid. generates, compressionand'rarefaction. waves both outwardly and inwardly with respect to. therotor slots. The inwardly directed pressure waves travel back through.the pipe 38; passing easily through" the plug 54" and thence into theliquid flowing in' the upper part of the pipe and through the surgetank.

It is important to note that the rotor 28 spins in air, since-liquidpassing through the rotor slots and through: the stator slots drops intothe lower housing 10' from which it is immediately. drained into the.pressure supply tanlc. Consequently the movement ofthe; rotor is. notimpeded by' the frictional; dragwhich would be presentif; the-entire.system were: immersed in liquid. This feature isofqgreat significance.from the standpoint of the efliciency; with which. the. system isoperated;

Asbest-showniin Fig. 3rthe rotor maytake. thezformis-a viewintcrosssectionwon; amenlargedscale showln'gthe: relationship. between:the rotor slots and sump: or low of a reaction turbine, in which case itsupplies its own motive power from the pressure of the liquid and themotor may be eliminated. Where the motor is used to drive the rotor, thefrequency of the sonic compression waves is a function of the speed ofthe motor and the number of slots in the rotor and stator, the rotorspeed being the variable factor. Where the rotor is self-driven as areaction turbine, the frequency will depend also upon the speed of therotor, and that in turn will depend upon the pressure of the liquidsupplied to it as well as the rate at which it is supplied, thesefactors being controlled by the setting of the relief valve 52 and thespeed at which the pump is driven.

In Figs. 25 the rotor-stator combination is shown in greater detail. Asbefore, there is provided a lower housing 60 having vertical reinforcingwebs 62 terminating in an appropriately formed base 64. The housing 60is provided with a centrally located tubular bearing housing 66 havingan upper bearing assembly 68 and a lower bearing assembly '70, bothbeing provided with suitable means for lubrication thereof. A shaft 67is supported in the bearings and connected at its lower end to a motorshaft 69. Propecting upwardly from the bottom of the housing 60 there isan integral annulus 72 upon which there is mounted a stator ring 74having a plurality of outwardly flaring ports or slots 76 and secured inposition by a series of bolts 78. It should be noted that the stator isso constructed as to be readily removable and replaceable by one havingslots of different configuration. In this way the shape of the generatedsound wave may easily be varied and controlled. Change in the wave shapeis accomplished by varying the flare angle of the stator slots. Withinthe stator and secured to the shaft 67 there is mounted a rotorconsisting of a bottom disk 80 secured by two rows of screws 84 and 85to an upper disk or plate 82. The bottom 80 of the rotor is machined toprovide a circular central chamber from which radiate a plurality ofmilled slots 86 each of which terminates at the periphery of the rotorin tangentially inclined jets 83, the jets being inclined rearwardlywith respect to the direction of rotation of the rotor.

A hollow casing 90 fits over the rotor and is secured to the lowerhousing 60 by a circumferential row of bolts 92. The housing 90 has acentral tubular portion enclosing a sleeve 96 which bears at its lowerend upon an annular sealing ring 94 resting upon the upper surface ofthe rotor disk 82 and flanged at its lower end to accommodate the lowerend of a compression spring 98 which bears at its upper end against aplate 100. A pipe 102 pierces the plate 100 and is received within theinterior of the sleeve 94. The spring 98 presses the flanged lower endof the sleeve 96, the seal 94 and the top of the rotor 82 in watertightrelation. A packing gland or other suitable sealing arrangement may beemployed in place of the system herein shown and described.

When liquid under pressure is supplied through the pipe 102 and into theinterior of the rotor 8082, it is forced outwardly of the rotor throughthe jets 88, and the reaction of this pressure through the jets 88serves to spin the rotor with the shaft 67.

As the rotor turns the flow of liquid therethrough it is interrupted asthe stator slots are opened and closed. Preferably the speed of therotor is governed to produce pressure pulses at a frequency equal tothat of the natural frequency of the system including the pipe 102 andthe tank which is coupled to it, since maximum amplitude is attained atthis natural frequency. The sound waves traveling up the pipe 102 arereflected at the junction between the pipe and the surge tank, theresult being that standing waves of considerable amplitude areestablished in the pipe.

Emphasis is laid upon the fact that the rotor spins in air, a fact whichmakes it possible to employ high rotor speeds, high frequencies, andhigh flow rates without wasting energy imparting angular momentum tofluid leaving the rotor. If it is desirable to produce cavitation in theliquid undergoing treatment, the supply system to the rotor may beoperated under pressure while the pressure in the treating circuit islow; if cavitation is not desired, the treating circuit can be operatedunder suflicient pressure to prevent it and thereby to establish thestanding wave field in the pipe. Preferably the pipe is tuned to thesiren either by adjustment or by precalculation.

Several important facts follow from the use of the back-generatedpressure pulses instead of the more conventional utilization of the downstream generated waves. If the down stream generated waves were to beemployed, the chamber surrounding the stator would have to be completelyimmersed in liquid. This liquid would exert a considerable frictionaldrag upon the rotor and thereby increase the work required to turn it.With the arrangement herein shown and described the rotor is spun inair, the most efficient manner of operation. Moreover, the flow passagesin the rotor are streamlined to avoid turbulence within them, and thepressure pulses travel efliciently back through the rotor passages andinto the treating system. By pressurizing the liquid supplied to therotor cavitation within it is effectively suppressed, whereas theelimination of cavitation within the slots of the stator is diflicult toavoid. Moreover it is practically impossible to avoid turbulence Withinthe stator slots.

It is also important to note that the system herein shown and describedmakes it convenient to treat liquids in a confined system withoutpassing them through the rotor-stator combination. Corrosive fluids orliquids of high viscosity could not for practical reasons be passedthrough the rotor-stator combination, but there is no impediment topassing them through a properly designed conduit and tank. As beforestated the separation of the treating circuit from that of therotor-stator combination also allows choice as to whether or notcavitation will be permitted within the treating circuit. Moreover thetreating circuit may be separately tuned to resonance by increasing ordecreasing the length of the conduit.

While there has been shown here a system designed for operation with aconfined treating circuit, it is equally possible to employ the liquidsiren as a means of generating pressure within an unconfined liquid. Insuch a case the inlet and surge tank are replaced by a suitable acoustichorn or other radiating device secured to the conduit.

A liquid siren of the type herein disclosed is useful to produce soundwaves of high intensity and, generally, in the frequency range of fromto 1,000 cycles per second, although frequencies as high as 10,000cycles may be obtained. The maximum sound output into water will exceed10 kilowatts.

Having now described and illustrated a preferred embodiment of theinvention, what I claim as new and desire to secure by Letters Patentis:

1. A liquid siren comprising a hollow rotor having peripheral openings,a stator surrounding said rotor and having ports adapted to be openedand closed by the rotation of the rotor, a first conduit connected tothe rotor, a housing encasing said stator and providing a drainagechamber of large capacity beneath said rotor, means for supplying liquidto said conduit, 2. second conduit connected to said first conduit, asolid plug separating said conduits, said plug having an acousticimpedance comparable to that of said liquid, said first conduit and plugproviding acoustical communication between said rotor and said secondconduit, and means for passing liquid through said second conduit.

2. A liquid siren comprising a slotted rotor, a stator surrounding saidrotor and having ports adapted to be opened and closed by the rotor, afirst conduit connected to said rotor, means for supplying liquid tosaid first conduit and rotor, a second conduit connected to the firstconduit, and a solid plug separating the first and second conduits, saidplug having an acoustic impedance approximately equal to that of saidliquid said first conduit and plug providing acoustical communicationbetween said rotor and said second conduit.

3. A liquid siren comprising an elongated pipe, a hollow rotor connectedto one end of said pipe, a stator surrounding said rotor, said rotor andstator having cooperating ports, a plug of solid material disposed insaid pipe to separate it into two compartments, means for supplyingliquid to the compartment nearest the rotor, and means for passing aliquid to be treated through the other compartment, said compartmentnearest the rotor and said plug providing acoustical communicationbetween said rotor and said other compartment, the

material of the plug having an acoustic impedance comparable to that ofthe liquid supplied to said rotor.

4. A liquid siren comprising an elongated pipe, a hollow rotor connectedto one end of said pipe, a stator surrounding said rotor, said rotor andstator having cooperating ports, a plug of solid material disposed insaid pipe to separate it into two compartments, a tank connected to theother end of said pipe, means for supplying liquid to the compartmentnearest the rotor, and means for passing a liquid to be treated throughthe other compartment and tank, said compartment nearest the rotor, saidplug and said other compartment providing acoustical communicationbetween said rotor and said tank, the material of the plug having anacoustic impedance comparable to that of the liquid supplied to saidrotor.

5. A liquid siren comprising a hollow rotor mounted for rotation upon avertical shaft, a motor connected to said shaft, a housing surroundingsaid rotor and providing a chamber beneath it, a drain connected to saidchamber, a stator disposed within said housing and surrounding saidrotor, said rotor and stator having cooperating ports, a conduit mountedabove and connected to said rotor, a plug of solid material disposed insaid conduit to separate it into two compartments, means for supplyingliquid to said rotor through one of said compartments, whereby liquidmay be passed through the rotor and stator and chamber to said drainpermitting 6 minimum frictional drag upon the rotor and means forpassing a liquid to be treated through the other of said compartments inthe said conduit, whereby said plug and the first-named compartmentprovide an acoustical communication between said rotor and said othercompartment.

6. A liquid siren comprising a slotted rotor, a stator surrounding saidrotor and having ports adapted to be opened and closed by the rotor, afirst conduit connected to said rotor, means for supplying liquid tosaid first conduit and rotor, a second conduit connected to the firstconduit, and a solid plug separating the first and second conduits, thefirst conduit and plug providing acoustical communication between saidrotor and said second conduit, said plug having an acoustic impedanceapproximately equal to that of said liquid.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,475,385 Hecht et al. Nov. 27, 1923 2,163,650 Weaver June 27,1939 2,248,459 Kiesskalt July 8, 1941 2,560,728 ee July 17, 19512,565,159 Williams Aug. 21, 1951 2,570,081 Szczeniowski Oct. 2, 19512,632,634 Williams Mar. 24, 1953

